Tailstock centre apparatus with a pressure indicator



June 29, 1965 v T wo 3,191,469

1 TAILSTOCK CENTRE APPARATUS WITH A PRESSURE INDICATOR Filed July 16,1962 2 Sheets-Sheet l June 29, 1965 T. WOZAR 3,191,469

TAILSTOOK CENTRE APPARATUS WITH A PRESSURE INDICATOR Filed July 16, 19522 Sheets-Sheet 2- United States Patent O 3,191,469 TAILSTOCK CENTREAPPARATUS WITH A PRESSURE INDICATOR Tiberius Wozar,Esslingen-Krummenaeker, Germany,

assignor to Bohner & Kiihle, Esslingen (Neckar),

Germany Filed July 16, 1962, Ser. No. 210,154 11 Ciaims. (Cl. 82-33) Theinvention refers to a tailstock centre apparatus and more particularlyto a tailstock centre apparatus having a pressure indicator.

There are known indicating devices for centre apparatus of the abovekind. However, these indicating devices are situated on the exterior ofthe centre housing so as to constitute an impediment for the operatorand to be exposed to damages. Other known indicating devices of the kindin question present the draw-back of being not sufliciently exact due tothe fact that the axial displacements of the centre are very small, andof it being very difficult to be protected against dirt, oil, and thelike.

It is, therefore, the main object of this invention to provide anapparatus of the above described kind in which the indicating devicedoes not substantially project beyond the peripheral surface of thehousing.

Another object of the. invention is to provide an apparatus of thegeneral character described which is reliable in service and can not beaffected by dirt or the like.

A further object of the invention consists in to provide an apparatus ofthe aforesaid kind with whichboring water or borings can not penetrateinto its interior.

Still another object of the invention is to provide an apparatus of theabove described character with which the pressure indications can beascertained with the operator inany position, even with an unskilledoperator and even with operators having visual defects.

. Yet another object of the invention is to provide an apparatus of theabove kind with which even smallest indications can be determined withgreatest accuracy.

A further object of the invention consists in to provide an apparatus ofthe above kind with which the pressure indications can be determinedvisually and-firstly-by touch.

Yet another object of the invention consists in to provide a device ofthe general character described having a pressure transmitting sleeveand an operating surface on the periphery of said sleeve and having atleast one pin slidably lodged in the centre house and the free interiorend of which bears against, and cooperates with, said operating surfaceon said sleeve, whereby upon axial displacement of said centre said pinis urged in outward direction by said operating surface and whereby uponthe pressure exerted upon said centre reaching a predetermined value theouter front end of said pin is brought to lie flush with the surroundingouter surface on said housing.

These and other objects, features, and advantages of the presentinvention will become further apparent from the following detaileddescription thereof.

Several embodiments of the invention are illustrated, by way of example,in the drawings, in which:

FIG. 1 is a longitudinal sectional view of a resilient tailstock centreaccording to the invention,

FIG. 2 is a cross-sectional view of the tailstock centre according toFIG. 1 taken along line IIII of FIG. 1,

FIG. 3 is an enlarged longitudinal sectional partial view of analternative embodiment of the invention,

FIG. 4 is a partial longitudinal sectional view of a further embodimentof the invention, and

"ice

, FIG. 5 is a partial longitudinal sectional view of another embodimentof the invention.

The tailstock centre shown in FIG. 1 contains a cup like shaped centrehousing 1 having a horizontally extending side wall 110 and an inwardlyextending bottom wall 111, and a centre 2 which is supported and guidedin the said housing by means of the front radial hearing 3, the rearradial bearing 4, and a thrust bearing 5. In the housing there is alsoaccommodated a pressure transmitting sleeve 6 having on its periphery abevelled operating surface 8 constituting a truncated cone taperingtowards the side remote from the work piece. The arrangement is suchthat the thrust bearing 5 bears on its front side facing the work piecethrough the medium of the annulus 50 against a shoulder 51 of the centre2 and on its rear side remote from the work piece against the front sidefacing the work piece of the inwardly extending wall 60 of the sleeve 6,the opposite side of said wall enclosing together with the front side ofthe bottom Wall 111 of said centre casing plate springs or Bellevillespring washers 7. The centre 2, the sleeve 6, and the housing 1 areco-axial. The pressure transmitting sleeve 6-which on its fore marginbears against the spring ring iii-participates in the longitudinalmotion of the centre 2 in direction of the arrow which longitudinalmotion is caused by the pressure exerted onto the centre 2 upon chuckingthe Work piece and during machining the same. This motion of the sleeve6 is transmitted via the operating surface 8 to a pin 9 regardless ofwhether the centre rotates or not during this motion transmittingoperation, said pin being sup ported in the housing 1 so as to beradially slidable therein.

The pin 9 is directed radially to the sleeve and resiliently bears withits inner endwhich conveniently may be rounded off-against the conicaloperating surface 8 of the pressure transmitting sleeve 6. To thispurpose, the pin 9 is mounted in a guide bushing 10 so asto be radiallyslidable therein, the said bushing 10 being screwed more or less deepinto a through-hole 11 in the side wall of the said housing. Because ofthis screw connection the bushing is adjustable within its through-hole.The pin 9 being provided with a guidedisk or shoulder 12 projectingradially to the pin, it is possible for the spring 13 which on its endremote of the centre bears against an inwardly projecting wall 101 ofthe bushing 10 to bear with its other end against the shoulder orguide-disk 12 of the pin 9 thereby tending to urge this latter towardsthe interior of the said housing 1 and towards the operating surface 8of the sleeve 6. Upon longitudinal movement of the centre 2 away fromthe work piece, the operating surface 8 of the sleeve 6 co-acts with theinner end 'of the said pin 9 so that this latter is moved to a smalleror greater extent in outward direction. The arrangement is thereby suchthat when the pressure actually exerted by the work piece onto thecentre reaches and has a certain predetermined magnitude, the flat outerend surface 91 of the outer end of the pin 9 lies flush with thesurrounding surface of the centre housing 1 and the ring shaped fiat endsurface of the guide bushing 10. This position of the pin 9 with itsouter end surface lying flush with the surrounding surface can be veryeasily and exactly ascertained by touch and also optically, especiallywith a certain angle of incidence of the light. In this way, thepressure exerted upon the centre at a certain moment can be exactlycontrolled.

In an embodiment not shown in the drawings, in the housing 1 there isaccommodated a sole pin 9 cooperating with the sleeve 6. In this case, asole pressure value can be controlled with this centre.

As shown in FIG. 2, it is possible without any difficulty to provideseveral pins h within the housing 1 and to arrange these pins so as tolie in spaced side by side relationship on the periphery of thehousing 1. It is thereby possible to give the individual pins 9different lengths in such a manner that the outer ends of the individualpins 9 lie each at different pressures flush with the ring-like outerfront surface of the corresponding guide bushing 10, there beingallotted to each of said pins a predetermined pressure value. Each ofsaid guide bushings 10 may be provided with a mark or a registrationindicating the exact value of the pressure allotted to the respectiveguide bushing. With a certain pressure, only a sole pin 9 lies flushwith the front surface of the corresponding bushing, this pin 9 therebyindicating in that moment the exact value of the pressure actuallyexerted in that moment upon the centre in question. In that moment, theouter front ends of the pins 9 of thevabove described series of pinswhich are allotted to a pressure greater than the pressure actuallyexerted upon the centre lie below the outer front surface of therespective guide bushing, whereas the outer front ends of the pinsallotted to a pressure lower than the pressure actually exerted projectbeyond the outer front surface of the guide bushings. However, the pinmovements caused by these pressure variations are so small that theoutwardly projecting ends of the pins do not constitute any hindrancefor the operator.

The above described effect can be obtained, as already said, by makingthe individual pins of different length. However, this effect can bealso obtained by screwing the guide bushings 10 more or less deep intothe housing or by combining these two measures namely variations in thelength of the pins and variations in the depth of the bushing. Anotherpossibility for adjusting the pressure value consists in tovary thespring force.

With the embodiment according to FIG. 3, the individual pins 99 arearranged so as to be spaced from one another in longitudinal directionof the centre housing 91. The pressure transmitting sleeve 96 hasseveral oblique operating surfaces 98 situated one behind the other asviewed in longitudinal direction of the centre. Thereby, these obliqueoperating surfaces can be so shaped as to constitute a portion of acorrespondingly designed groove. The succession of the different pins 90and the succession ofthe different operating surfaces are related to oneanother in like manner as are the graduations on a Vernier scale withthose on the main scale, i.e. the distances between the successiveoperating surfaces are somewhat displaced with respect to the distancesbetween the successive pins so that the individual pins 90 runsuccessively-and not simultaneouslyonto the respective operating surfaceallotted thereto, thereby showing and indicating the respective centrepressure. In this case also the arrangement may be such that only onepin 2% indicates the corresponding pressure at a time, whereas the otherpins 9 have not yet reached their flushing position or have alreadypassed the bushing 10. As in the previously described. embodiments ofthe invention, the pins are slidably accommodated in guide bushings 80within the holes 81 and provided with annular projections 82 which areunder the influence of springs 83. A thrust bearing for supporting thecentre 84 is shown at 85. The pressure transmitting sleeve 96 is underthe influence of the Belleville spring 97. In the embodiment accordingto FIG. 4, the operating surface 122 is provided on the outer front face120 of the pressure transmitting sleeve 121, whereby a sole pin 123 orseveral pins are accommodated in guide bushings 124 in the housing 126and extending longitudinally to the centre 125. The thrust bearingsupporting the centre 125 is shown at 127. In the case of several pins123 these pins are arranged along a curve on the outer front end of thehousing 126. In this case, the pins 123 penetrate axially through theBelleville springs 128.

A further embodiment of the invention is shown in PEG. 5. In this case,the pressure transmitting sleeve 1% has a radial projection 131 lodgedwithin the recess 132 of the housing 133, this projection presenting onits side turned away from the work piece an operating surface 134 whichcooperates with the pins 135 slidably arranged in the guide bushings136. Pins and guide bushings extend thereby longitudinally to thehousing 133 of the centre 137.

Although my invention has been illustrated and described with referenceto the preferred embodiments thereof I wish to have it understood thatit is in no way limited to the details of such embodiments, but iscapable of numerous modifications within the scope of the appendedclaims.

Having thus fully disclosed my invention, what I claim 1s:

1. A tailstock centre apparatus comprising in combination a centre meansextending centrally and longitudinally of the apparatus; a sleeve meansco-axil with and surrounding, said centre means, and having a radiallyextending wall portion, said centre means being supported for rotarymovement within said sleeve means, said centre means and said sleevemeans being interconnected for resilient to and fro movement in theaxial direction; a hollow housing co-axial with, and surrounding, saidsleeve means and having a radially extending wall portion opposite saidradially extending wall portion of said sleeve means, said sleeve meansand said centre means being axially displaccable within said housing;resilient means resiliently actin in the axial direction and interposedbetween said radially extending wall portions of said sleeve means andsaid housing; at least one throughbore in saidhousing extending from theoutside to the interior thereof; an operating surface on said pressuretransmitting sleeve; 21 pin having an inner and outer end and receivedin said through-bore for slidable to and fro movement; the inner end ofsaid pin bearing against, and cooperating with, said operating surface,whereby upon an axial movement of said centre taking place under theinfiuence of pressure exerted by the work-piece upon said cen re amovement of said pin relative to its respective through-bore is causedto take place, said pin being of such length that upon the pressureexerted by the workpiece upon said centre reaching a predetermined valuethe outer front end of the pin lies flush with the outer surface of saidhousing surrounding said pin.

2. The tailstock centre apparatus set forth in claim 1, in which saidoperating surface is on the periphery of said pressure transmittingsleeve and constitutes a bevelled surface tapering towards the sideturned away from the work piece.

3. The tailstock centre apparatus set forth in claim 2, wherein severalpins and through-bores are provided, in co-operative relationship withsaid operating surface, each of said pins being aliotted to apredetermined pressure value, whereby upon the pressure exerted by thework-piece reaching successively one of said predeterminded pressurevalues only one of said pins namely the pin allotted to the respectivepressure value is so moved as to bring its outer front end to lie flushwith said outer surface of said housing surrounding said pin.

4. The taiistock centre apparatus set forth in claim 3, wherein saidoperating surface cooperating with said several pins runs around theperiphery of said pressure transmitting sleeve and constitutes theperiphery of a truncated cone tapering towards the side turned away fromthe work piece.

5. The tailstock centre apparatus set forth in claim 4, wherein saidseveral pins and through-bores are spacedly arranged along the peripheryof said housing in a radial plane. a

6. The taiistock centre apparatu set' forth in claim 3, wherein saidseveral pins and through-bores are arranged on said housing so as to beinterspaced in axial and longitudinal direction, said pressuretransmitting sleeve being provided with several operating surfacesarranged so as to be interspaced in axial and longitudinal direction andcorresponding in number to said several pins, the succession of saiddifferent pins and the succession of said different operating surfacesbeing related to one another in like manner as are the graduations on aVernier scale with those on the main scale, the distances between thesuccessive operating surfaces being somewhat displaced with respect tothe distances between the successive pins.

7. The tailstock centre apparatus set forth in claim 3, wherein saidseveral pins are of different length.

8. The tailstock centre apparatus set forth in claim 1, wherein said pinis accommodated Within a guide bushing fixedly arranged in saidthrough-bore in said housing, whereby upon the pressure exerted uponsaid centre reaching a predetermined value the outer front end of saidpin lies flush with the outer front surface of said bushing.

9. The tailstock centre apparatus set forth in claim 1,

wherein said counter-bore extends axially with respect to said centre,said through-bore being located in the rear wall of said housing.

19. The tailstock centre apparatus set forth in claim 9, wherein saidoperating surface is provided on the rear face of said sleeve facingsaid rear wall of said housing receiving said pin.

11. The tailstock centre apparatus set forth in claim 9, wherein saidoperating surface is provided on a collarlike radial projection of saidpressure transmitting sleeve.

References Cited by the Examiner UNITED STATES PATENTS 2,844,063 7/58Rohm 8233 FOREIGN PATENTS 63 3,224 7/ 36 Germany. 480,487 4/53 Italy.

WILLIAM W. DYER, IR., Primary Examiner.

1. A TAILSTOCK CENTRE APPARATUS COMPRISING IN COMBINATION A CENTER MEANSEXTENDING CENTRALLY AND LONGITUDINALLY OF THE APPARATUS; A SLEEVE MEANSCO-AXIAL WITH AND SURROUNDING, SAID CENTRE MEANS, AND HAVING A RADIALLYEXTENDING WALL PORTION, SAID CENTRE MEANS BEING SUPPORTED FOR ROTARYMOVEMENT WITHIN SAID SLEEVE MEANS, SAID CENTRE MEANS AND SAID SLEEVEMEANS BEING INTERCONNECTED FOR RESILIENT TO AND FRO MOVEMENT IN THEAXIAL DIRECTION; A HOLLOW HOUSING CO-AXIAL WITH, AND SURROUNDING, SAIDSLEEVE MEANS AND HAVING A RADIALLY EXTENDING WALL PORTION OPPOSITE SAIDRADIALLY EXTENDING WALL PORTION OF SAID SLEEVE MEANS, SAID SLEEVE MEANSAND SAID CENTRE MEANS BEING AXIALLY DISPLACEABLE WITHIN SAID HOUSING;RESILIENT MEANS RESILIENTLY ACTING IN THE AXIAL DIRECTION AND INTERPOSEDBETWEEN SAID RADIALLY EXTENDING WALL PORTIONS OF SAID SLEEVE MEANS ANDSAID HOUSING; AT LEAST ONE THROUGHBORE IN SAID HOUSING EXTENDING FROMTHE OUTSIDE TO THE INTERIOR THEREOF; AN OPERATING SURFACE ON SAIDPRESSURE TRANSMITTING SLEEVE; A PIN HAVING AN INNER AND OUTER END ANDRECEIVED IN SAID THROUGH-BORE FOR SLIDABLE TO AND FRO MOVEMENT; THEINNER END OF SAID PIN BEARING AGAINST, AND COOPERATING WITH, SAIDOPERATING SURFACE, WHEREBY UPON AN AXIAL MOVEMENT OF SAID CENTRE TAKINGPLACE UNDER THE INFLUENCE OF PRESSURE EXERTED BY THE WORK-PIECE UPONSAID CENTRE A MOVEMENT OF SAID PIN RELATIVE TO ITS RESPECTIVETHROUGH-BORE IS CAUSED TO TAKE PLACE, SAID PIN BEING OF SUCH LENGTH THATUPON THE PRESSURE EXERTED BY THE WORK-PIECE UPON SAID CENTER REACHING APREDETERMINED VALUE THE OUTER FRONT END OF THE PIN LIES FLUSH WITH THEOUTER SURFACE OF SAID HOUSING SURROUNDING SAID PIN.